Optical navigation systems detect relative movements between the optical navigation systems and navigation surfaces to perform tracking operations. An optical navigation system uses a light source to generate illumination light on a navigation surface and an image sensor to successively capture frames of image data of the navigation surface using reflected illumination light. The optical navigation system compares the successive frames of image data and estimates the relative movements between the optical navigation system and the navigation surface based on the comparison between the current frame of image data and a previous frame of image data. The optical navigation system is able to track the relative movements between the optical navigation system and the navigation surface by continuously capturing and comparing frames of image data.
Optical navigation systems are commonly used in optical computer mice to track the movements of the mice relative to the navigation surfaces on which the mice are manually manipulated. Optical navigation systems are also used in optical finger navigation devices. In an optical finger navigation device, the surface of a finger is used as the navigation surface to track the relative movements of the finger relative to the optical finger navigation device.
A conventional optical finger navigation device includes a light source and a sensor chip with an image sensor array, which are mounted on a printed circuit board. The optical finger navigation device may include an optical element to optically manipulate light from the light source, which is reflected from the finger, onto the image sensor array of the sensor chip. However, the optical element may not be cost effective, which increases the overall cost of the optical finger navigation device.
Thus, there is a need for a lower cost optical element, which can be used in an optical finger navigation device to optically manipulate light reflected from a finger onto an image sensor array of the device.